fix: address PR #745 review comments

- .gitignore: add missing trailing newline
- Dockerfile: remove misleading || echo fallback in Playwright install
- index.ts: truncate long paths from beginning instead of end in warning box
- verify-claude-auth.ts: use effectiveAuthMethod to prevent undefined authType
- agent-context-parser.ts: handle claude-opus alias as Opus 4.6
- thinking-level-selector.tsx: improve model prop documentation

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/ui/src/components/views/board-view/shared/thinking-level-selector.tsx

@@ -9,7 +9,8 @@ interface ThinkingLevelSelectorProps {
   selectedLevel: ThinkingLevel;
   onLevelSelect: (level: ThinkingLevel) => void;
   testIdPrefix?: string;
-  /** Optional model ID to filter available thinking levels (e.g., Opus 4.6 only shows None/Adaptive) */
+  /** Model ID is required for correct thinking level filtering.
+   *  Without it, adaptive thinking won't be available for Opus 4.6. */
   model?: string;
 }